You have 1 of 2 problems eather it's low on coolant or its the head gaskets going bad I've seen this 100 time or more time in my shop I had for over 37 years and its not just caddies its anything with coolant and head gaskets in it . There not completely blown yet but the end is coming soon what happens is its blowing compression into the cooling system and it is aerating the system . A good way to test it is when it's cold put a pressure gauge on the radiator ,
.where the cap goes start it up if it starts building pressure in a couple of minutes that a good sign . If you don't have a gauge you can feel the upper hose if it gets hard before it gets warm that's also a sign ... Does it have hi mileage? Any more question please feel free to ask .